Setting DXF colors via Fiona

Question

One might expect that the "Color" CAD field would control this, but the driver doesn't allow it to be set.

schema = {'Layer': 'str', 'Color': 'int'}

with fiona.open(path, 'w', 'DXF', schema=schema) as f:
    f.writerecords(records)

Gives:

ERROR: failed to export vectors: DXF layer does not support arbitrary field creation, field 'Color' not created.

The driver documentation suggests that it attempts to interpret OGR feature styles, but I see no mention of these in the Fiona docs. Is it possible to set arbitrary colors with Fiona?

Answer 1

I had the same question. I did not find a solution to this direct question, but implemented a workaround using ezdxf.

I export from geopandas (using a fiona driver), import into ezdxf, set the layer colors, and resave.

doc = ezdxf.readfile(inputFileName)
layerDict = getLayerDic(doc)
#... manipulations of that same file in geopandas ...
exportGPDwPolygonstoDXF(df).to_file(outputFileName)
resaveWLayerColor(outputFileName, layerDict)

This is really a clunky workaround, but it may provide some short term solution.

def exportGPDwPolygonstoDXF(df):
    df1 = df.copy()
    df1['geometry'] = df['geometry'].apply(lambda x: LineString(x.exterior.coords))
    return df1
def resaveWLayerColor(fileName, layerDict):
    doc = ezdxf.readfile(fileName)
    modelspace = doc.modelspace()
    for layer in doc.layers:
        layer.color = layerDict[layer.dxf.name.split('_')[0]]
    doc.saveas('{}_c.dxf'.format(os.path.splitext(fileName)[0]))
def getLayerDic(doc):
    layers = doc.layers
    return {lay.dxf.name: lay.color for lay in layers}